May 8-16, 2006
Midwest Weekly Highlights - May 8-16, 2006
The second week of May was headlined by a stagnant weather pattern that affected nearly each state in the Midwest! Precipitation was largely above average, and temperatures were below, to significantly below average for this time of year. The average daily temperature departure map for the Midwest illustrates that much of the region was below normal for this time of year (Figure 1). Average daily mean temperature departures for the second week of May ranged from 3-4°F above normal in extreme northeastern lower Michigan to a whopping 4-6°F below normal across much of Illinois, Wisconsin, Missouri, Iowa, and Minnesota. However, the average daily temperatures don't tell the whole story, as minimum temperatures were generally or only slightly below normal for this time of year. It was, however, the departure from normal daytime high temperatures that was most noticeable across the region, ranging from 8 to 12°F below average across Illinois, Wisconsin, Indiana, and Ohio (Figure 2).
Precipitation for the
week was fairly widespread across the Midwest, with the heavier
precipitation falling across eastern Illinois, Indiana, Michigan,
Wisconsin, and Ohio. This week, northern Missouri, southern Iowa,
and portions of eastern Kentucky experienced precipitation
deficits, where total precipitation ranged from 10 to 50% of normal.
Meanwhile, much of Wisconsin, Michigan, Indiana, and Ohio
saw significantly above average precipitation. In these areas,
precipitation totals were generally 100 to 200% of the normal
precipitation, with the Upper Peninsula of Michigan taking the cake at
a staggering 700% of normal (Figure 3).
In fact, the entire state of Michigan saw precipitation totals
that were greater than 200% of normal for this time of year! On
account of the beneficial precipitation
across much of the
Midwest
this week, there was little change in the drought status (Figure 4).
Flooding Rains and Severe Weather
A slow moving cold front moved through the Midwest on May 8-10, bringing several rounds of thunderstorms, many of which were severe. On the 8th, hail was reported as far north as north-central Minnesota, while additional severe thunderstorms dotted western Iowa and southern Missouri (Figure 5). In Mower and Fillmore Counties in southeastern Minnesota, hail to the size of nickels and quarters fell, covering the ground in some communities for a span of 3 hours and filling drainage ditches! Flooding rains associated with more severe thunderstorms on May 10 prompted officials in Carlisle County, Kentucky to close one of the county schools. In excess of 5 inches of rain fell during a 24-hour period (Figure 6), forcing at least 9 homes to be evacuated. Several persons had to be rescued from tops of cars as they unsuccessfully tried to cross flooded streets. In West Viola, KY, a Baptist church suffered in excess of $50,000 in damages from floodwaters which covered the inside of the church up to six inches deep in spots. In this month alone, Graves County, KY has received almost 10 inches of rain. The National Weather Service in Springfield, MO assembled a neat graphic which outlines the mechanisms responsible for the flash flooding (Figure 7, NWS SGF).My Head Keeps Spinning...
On May 10-11, an area of low pressure moving northeast from Texas and Oklahoma underwent explosive cyclogenesis (the rapid intensification of low pressure) across Indiana. This low deepened from 1004mb (29.92 inHg) on the morning of May 10, to 983mb (29.03 inHg) on the morning of May 11. The significant drop in pressure resulted in a dramatic increase in wind speeds, in combination with periods of rain. The lowest pressure recorded during the height of the intensification was at Muskegon, MI, where sea-level pressure bottomed out at 28.97 inHg! In Grand Rapids, MI, a new monthly low pressure was set of 29.08 inHg, breaking the old monthly record of 29.10 inHg set in May of 1997 (and pressure records extend back to 1897).
In northern Wisconsin and the Upper Peninsula of Michigan, winter weather advisories were posted as the intense low brought down cold air from Canada and mixed it with ongoing precipitation (Figure 8). This changed the precipitation type from rain during the day to a heavy, wet snow during the overnight hours of May 10-11. When all was said and done, several stations across north-central Wisconsin picked up some hefty amounts of snow. As much as 8.0" of snow was reported in Pence, WI and Montreal, WI where the weight of the snow in concert with high winds was causing 60ft pine trees to fall down along with several tree branches.
High winds associated with the rapid deepening were experienced across several Midwest states. The following table consists of some selected peak wind gusts recorded on May 11 from the synoptic scale storm (Figure 9, NWS Green Bay, WI):
| Gills Rock, WI | 70mph |
| Stannard Rock, MI | 58mph |
| Sturgeon Bay, WI | 55mph |
| Sheyboygan, WI | 50mph |
| Green Bay, WI | 49mph |
| Madison, WI | 48mph |
| DeKalb, IL | 48mph |
| Muskegon, MI | 44mph |
The non-thunderstorm high winds caused quite a bit of damage across the region. In Chicago, IL, there were approximately 100 reports of tree limbs and/or power lines down across the city in Cook County. In Fulton County, IL a large tree fell on a house resulting in roof damage. In Allegan, MI, one person was killed and one was injured when strong winds blew a large tree limb onto a passing vehicle, killing the 45-year old driver and injuring the passenger. In Door County Wisconsin, 28,000 customers were without power as the winds blew over several power poles, and made sailing conditions on Green Bay and Lake Michigan dangerous, which resulted in the cancellation of the Washington Island Ferry [which runs from northeastern Door County to Washington Island].
Checking the Calendar...March or May?
The upper-level low (Figure 10) that persisted across the Midwest during the week also produced some record cold weather, primarily in the record low maximum category. From May 11-16 persistent cloud cover, breezy conditions, and generally showery weather dominated almost every state in the 9-state MRCC region (Figure 11). The cloud cover and showers kept daytime maximum temperatures well below normal for this time of year (Figure 12). Several locations across the Midwest logged their coldest maximum temperatures for this period, and are summarized in the table below. In addition, the following figure illustrates the expanse of the cold air, marked by those stations that failed to reach 50°F on May 12 (Figure 13).
| Date | Location | New Record | Previous & Year |
| May11 | Marquette, MI | 37°F | 37°F, 1970 |
| May 12 | Urbana, IL | 48°F | 53°F, 1892 |
| Peoria, IL | 48°F | 48°F, 1914 | |
| Lincoln, IL | 51°F | 52°F, 1918 | |
| Moline, IL | 46°F | 47°F, 1966 | |
| Dubuque, IA | 44°F | 44°F, 1966 | |
| Indianapolis, IN | 49°F | 52°F, 1892 | |
| Fort Wayne, IN | 46°F | 49°F, 1960 | |
| South Bend, IN | 43°F | 46°F, 1966 | |
| LaCrosse, WI | 44°F | 48°F, 2005 | |
| Rochester, MN | 43°F | 47°F, 1966 | |
| Appleton, WI | 44°F | 44°F, 2002 | |
| Oshkosh, WI | 45°F | 45°F, 2002 | |
| Manitowoc, WI | 43°F | 43°F, 2002 | |
| Madison, WI | 46°F | 47°F, 2002 | |
| May 13 | Indianapolis, IN | 50°F | 53°F, 1895 |
| May 14 | Rolla/Vichy, MO | 56°F | 56°F, 1967 |
The long-range forecast for the third week of May is for a continuation of above normal precipitation but with a moderation in temperatures across the Midwest. Will locations that were excessively below normal (temperature-wise) this week rebound next week? Find out in next week's edition of the Midwest Climate Watch.
Kruk